Currently, an Optical Switching Fabric (Optical Switching Fabric, OSF for short) refers to an internal switching network of a router, a switch, an Optical Transport Network (Optical Transport Network, OTN for short) switching device, and the like. Generally, for ease of description, the OSF is divided into an optical switching matrix (Optical Switching Matrix, OSM for short) part for completing a switching function, and a control part for implementing switching scheduling or control.
A mainstream manner for supporting small-granularity switching in the OSM is still a time division switching (Time Division Switching, TDS for short) manner. The TDS includes using of an optical burst (Optical Burst, OB for short), an optical packet (Optical Packet, OP for short), or an optical cell (Optical Cell, OC for short). The so-called time division switching refers to a switching manner in which time is divided into several non-overlapping timeslots, different subchannels are established by using different timeslots, and service data is transmitted from an input point to an output point by using a timeslot switching network.
In a time division switching system, a switching speed of an optical component in the OSM determines a switching granularity. The switching speed of the optical component determines an interval length between optical bursts, and to ensure a specific bandwidth utilization rate (for example, to ensure a physical bandwidth utilization rate of 90%, an optical burst length must be about 10 times the interval length between the optical bursts), this also restricts the optical burst length, which thereby determines the switching granularity.
A finest switching granule may exist in a switching network of a routers or a switch, which generally requires implementation of switching at a granularity of a 64-byte cell (Cell). If an optical switching fabric apparatus is to be introduced to a router or a switch, the following is required:
In a case in which an interconnection line speed is 10 Gbps (Gbps, 10 bits per second), a switching granularity length (temporal) is: 64 Bytes×8/10 Gbps≈50 ns (ns, 10−9 second); and to ensure a relatively high bandwidth utilization rate (assuming that the switching granularity length is 10 times the interval, the physical bandwidth utilization rate is greater than 90%), an optical burst interval is 5 ns.
In a case in which an interconnection line speed is 25 Gbps, the switching granularity length is 20 ns, and the optical burst interval is 2 ns.
However, another requirement of the optical switching fabric apparatus used in a router or a switch is a capacity. With rapid growth of user traffic, a greater capacity of the optical switching fabric apparatus is also required.
Therefore, how to design an optical switching fabric apparatus with a large capacity and a relatively fast switching speed becomes an issue to be urgently solved currently.